How can I swim faster?

Transcription

How can I swim faster?
Coach Chan Mee Lee
© 2010 Current Club Ltd.
1
Simple Math
In general,
Distance (m) = Speed (m/sec) x Time (sec)
Time (sec) = Distance(m)
Speed (m/sec)
In swimming,
Speed (m/sec) = Stroke Length (m/stroke) x Stroke Rate (stroke/sec)
Therefore,
Time (sec) =
Distance (m)
Stroke Length (m/stroke) x Stroke Rate (stroke/sec)
* Note: m = meter, sec = second
2
Example
What is the time of swimming a 50 meters Freestyle at
stroke rate of 1.5 stroke per second and stroke length of 1
meter per stroke?
3
Key to Increase Speed
Speed (m/sec) = Stroke Length (m/stroke) x Stroke Rate (stroke/sec)
1. Propulsive
Force
3. Stroke
Form
2. Minimization
of Resistance
4
Newton’s First Law
 A body acted on by no net force moves with constant velocity (which
may be zero) and zero acceleration.
That means, an object will always continue moving at its current speed and in its current
direction until some force causes its speed or direction to change.
An object that is not in motion (velocity = zero), which will remain at rest until some force
causes it to move.
If Newton is right, how come after a swimmer push off
from the wall, one will slow down and eventually come to
a stop?
Ans: DRAG!
5
Newton’s Second Law
 If a net external force acts on a body, the body accelerates. The
direction of acceleration is the same as the direction of the net force.
The net force vector is equal to the mass of the body times the
acceleration of the body.
Mass = Density x Volume
Sum of the
forces
acceleration
Therefore,
6
Free Body Diagram of A Swimmer
Source: Cislunar Aerospace, Inc.
7
Newton’s Third Law of Motion

If body A exerts a force on body B (an “action”), then body
B exerts a force on body A (a “reaction”). These two forces
have the same magnitude but are opposite in direction.
These two forces act on different bodies.
Apply to swimming,
F swimmer on water = - F water on swimmer
8
•
Increase muscular force
Muscular Strength: Endurance and Power
Muscle mass
•
Increase flexibility
Maximize range of motion, esp. shoulders and ankles joints.
Stiffness in joints = energy inefficiency
•
Stroke coordination
9
Types of Drag
1. *Pressure/ Form drag (Fp),
2. Surface/ Friction drag (Fs) and
3. *Wave drag (Fw)
Total Drag (FDrag) a swimmer
encounters
FDrag = Fp + Fs + Fw
10
Minimization of Resistance
• Decrease of drag & turbulence
o
o
o
Decrease body cross-sectional area
Body alignment- Leg and hip sinking disturbed
streamlined
Streamline body position (front & back, left and right),
including head position.
11
Streamline
Ian Thorpe testing in the wind tunnel
Source: http://www.swim.ee/adidas
12
Streamline
Ian Thorpe testing in the water
Source: http://www.swim.ee/adidas
Natalie Coughlin
Source: http://swimtelligence.blogspot.com
13
Streamline
14
Minimization of Resistance (cont’d)
15 meters underwater kicks

History
Denis Pankratov
Russian

Butterfly swimmer
1996 Summer Olympics in Atlanta, Georgia, USA
100 Bu- 1st lap more than 25 m underwater, 2nd 15 m
FINA rule changed
Swimming not more than 15 meters after the start and each
turn.
15
Stroke formIndividual differences (variation between individuals)
o
Physique
16
Stroke form (cont’d)
o
Density
Water=1.0 g/cm3
Ocean Water= 1.03 g/cm3
Dead Sea = 1.24 g/cm3
Body Fat= 0.9 g/cm3
Muscle= 1.06 g/cm3
Human body: 0.9-1.0 g/cm3
o
Learning ability
oThe Eagerness to change
oSeriousness in performing drills
oPractice makes perfect
Perfect practice makes perfect
17
Sports Technology
Hi-Tech swimsuits claim to
o decrease surface drag
o decrease pressure drag
V-shaped ridges pattern - mixing/ redirect flow pattern to decrease pressure
differential
o Increase muscle compression
o Increase buoyancy - less drag
E.g. Speedo FastSkin, Arean X-Glide, Adidas JetConcept
FINA Rules By-Laws
 BL 8.2 In swimming competitions the competitor must wear only one swimsuit in one or two
pieces. No additional items, like arm bands or leg bands shall be regarded as parts of a swimsuit.
 BL 8.3 From January 1, 2010 swimwear for men shall not extend above the navel nor below the
knee, and for women, shall not cover the neck, extend past the shoulder, nor shall extend below
knee. All swimsuits shall be made from textile materials.
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FINA Requirements for Swimwear
Swimsuits criteria:
Material:
o Flexibility: the material shall be flexible and soft folding.
o Regular flat material: The material shall be regular and flat. The material shall not form
outstanding shapes or structures, such as scales.
o Thickness: The material used shall have a maximum thickness of 0.8mm.
o Buoyancy: The swimsuit shall not have a buoyancy effect above 0.5 Newton measured after
application of vacuum.
o Permeability: material(s) used must have at any point a permeability value of more than 80
litres/meter2/second.
Construction:
o External stimulation or influence: swimsuits which include any system providing external
stimulation or influence of any type, including pain reduction, chemical/medical substance
release, electro-stimulation etc. are prohibited.
Caps and goggles criteria:
o Independent item: the cap shall not be attached to the swimsuit or goggles nor be in
continuity therewith (no "hood" or "mask" effect).
19
Sports Technology
Design of swimming pool
• Anti-waves swimming lanes
• 10 lanes with gutter placed at the same level of water
• Location of water outlet and inlet
20
References





BrainyWeightLoss.com. Apples and Pear: Which of the 2 Basic Female Body Shapes do You Have?.
Retrieved July 3, 2010, from http://www.brainyweightloss.com/apples-and-pears.html.
Brandon G. (2010). Speedo FastSkin- One side of the Story. Retrieved June 30, 2010, from
http://fastskin.blogspot.com/2010/02/fastskin-innovative-technology-for-best.html.
H.D. Young. & R.A. Freedman (2004). University Physics with Modern Physics (10th ed.). Addison
Wesley.
Toussaint , Huub M. (2002). THE FAST-SKIN“ ‘BODY’ SUIT: HIP, HYPE, BUT DOES IT REDUCE DRAG
DURING FRONT CRAWL SWIMMING?. Retrieved June 30, 2010, from
http://www.coachesinfo.com/index.php?option=com_content&view=article
&id=192:swimming-isbs-fastsking&catid=74:articlesoncoachesinfoservice&Itemid=136.
Woman’s Magazine. (2010). How To Test Your Body Shape?. Retrieved June 30, 2010, from
http://www.womansmagazine.net/how-to-test-your-body-shape.html.
21
Questions?
Coach Chan Mee Lee
[email protected]
22

How can I swim faster?

Transcription

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